Muffled resonant pulse jet combustion heating device



y ,1955 B. LAFFERENTZ EIAL MUFFLED RESONANT PULSE JET comsus'rrou HEATING mgvxcs Filed March 17, 1953 I l a; 1 155mm $4 M MC 73% PT ATTORNEYS g4]! 1111/ 11 1 1 II 1/ .f I I I I A 4! United States Patent MUFFLED RESONANT PULSE JET COMBUSTION HEATING DEVICE Bodo Laffercntz, Nussdorf, near Uberlingen am Boden See, and Ludwig R. Huber and Bernhard E. Strittmatter, Uberlingen am Boden See, Germany, assignors, by mesne assignments, to Swingfire (Bahamas) Limited, Nassau, Bahamas, a corporation of the Bahamas Application March 17, 1953, Serial No. 342,846

Claims priority, application Germany April 5, 1952 7 Claims. (Cl. 158-4) This invention relates to a heating device comprising a resonant pulse jet combustion device provided with means for adjustably feeding a firing fuel into the exhaust pipe of the combustion device independently of the fuel fed to the pulse jet combustion device. Such a device is described in our copending application Serial No. 302,728,

filed August 5, 1952. A device of this nature does not require draft inducing means such as a stack or chimney and its heat output can be varied within a wide range but it produces a loud noise when in operation.

The present invention relates to an improved device of the type described in which a silencer or muffler is connected to the mouth of the exhaust pipe of the resonant pulse jet combustion device, and the independently fed firing fuel is sprayed or fed into the muffler and then mixed with fresh air in a mixing nozzle and fed into the firebox, where it is burned. With the arrangement according to the present invention, the noise of operation is almost completely eliminated, while combustion of the independently fed firing fuel is maintained with undiminished intensity. This fact is surprising, since those skilled in the art had heretofore assumed that strong acoustic vibrations produced in the firebox were essential to maintaining combustion of high intensity.

The vaporization of the firing fuel in the mufiler may be produced in various ways. In devices of relatively low capacity, it is sufficient to introduce the firing fuel into the muffler in drops, whereupon the turbulent whirling exhaust gases in the muffler break up the fuel drops into minute droplets and partially vaporize them. In devices of higher capacity, it is desirable to inject the fuel into the mufller under pressure through a spray nozzle. When the firing fuel introduced is diesel oil or gas oil, it may be introduced directly into the exhaust pipe of the resonant pulse jet combustion device by means of a nozzle opening into the exhaust pipe at a point which may, for example, be about ten to fifteen centimeters in advance of the mouth of the pipe that opens into the muffler. The fuel oil is thereby effectively vaporized and preheated.

In describing the invention in detail, reference will be made to the accompanying drawing, in which certain em- I bodiments thereof are illustrated.

In the drawing:

Fig. 1 is an elevation, partly in section, illustrating a heating device embodying the invention in which the firing fuel is injected into the mufiler through a spray nozzle;

Fig. 2 is a sectional elevation of a mufiler for use with the combustion device of Fig. 1 in which the firing fuel is introduced into the exhaust pipe of the resonant pulse jet combustion device; and

Fig. 3 is a simplified and diagrammatic representation of a cyclone-type muffier for combustion devices according to the invention.

As shown in Fig. 1, the resonant pulse jet combustion device illustrated includes a combustion chamber 1 which is fed with operating fuel, such as gasoline or benzol, from a carburetor 2 and is supplied with air to support combustion through a check valve 3. The exhaust pipe 4 of the 2,707,515 Patented May 3, 1955 device which, with the combustion chamber 1, forms a resonator, includes a coil within the firebox 20 and has a mouth 5 connected to a muffler chamber 6.

A mixing tube 7 is connected to the mufiler chamber 6 on the opposite side thereof from the exhaust pipe connection thereto, and a spray nozzle 8 through which the firing fuel is fed under pressure from a tank 9 opens into the mixing tube 7, Pressure for feeding the firing fuel is produced by connecting the head space of the tank 9 with the exhaust pipe 4 through a pipe 10 provided with a check valve 11 which transmits pressure impulses only. from the exhaust pipe 4 to the tank 9. As is diagrammatically illustrated by the restricted bypass 36, the check valve 11 does not close completely so that the pressure built up in the head space of the tank 9 reaches a predetermined value only during operation and this pressure leaks off after operation of the device is stopped.

The combustion chamber 1 is provided with a surrounding jacket 12 which terminates in a burner nozzle 13 opening into the firebox 29. The annular space 14 between the combustion chamber 1 and the jacket 12 is provided on its underside with an inlet funnel 15 which, in conjunction with the outlet tube 16 of the mufiler chamber 6, forms an injector type mixing nozzle. The mixture leaving the muffler chamber 6 consists of hot exhaust gases from the resonant pulse jet combustion device 14 and the vaporized firing fuel introduced into the mufiler chamber through the spray nozzle 8. This mixture is mixed with air at the mixing nozzle 1516 and then flows through the annular space 14 to the burner nozzle 13, at the mouth of which additional air to support combustion is introduced through an annular opening around the nozzle, as is indicated by the arrows P.

To insure positive ignition at the burner nozzle 13, the adjacent end of the combustion chamber 1 is provided with a cup-shaped depression 17 enclosed by a perforated collar 18. Because of the retardation of heat dissipation therefrom, the depression 17 is rapidly raised to a red heat when the resonant pulse jet combustion device is in operation, and so ignites the fuel mixture penetrating the perforations in the collar 18. The mixture then burns in a flame 19 within the firebox 20.

A small hand pump 22 is connected to the air induction pipe 33 between the check valve 3 and the intake mufiier 21. To start operation of the device, the glow coil 37 of the ignition plug 23 is first heated electrically, whereupon air is blown into the combustion chamber 1 by operation of the hand pump 22. This blowing in of air causes fuel to be drawn from the carburetor 2, and the fuel and air mixture is ignited by the glow coil 37 within the combustion chamber 1. Thereupon, periodic detonations occur within the combustion chamber at the acoustic resonant frequency of the device and the exhaust gases from such detonations flow through the exhaust pipe 4 into the mufiler 6 and heat the muifier. After a brief period of operation, the depression 17 becomes red hot and the mufiier 6 is hot enough to vaporize the firing fuel. The fuel valve 24 in the supply pipe 41 for the nozzle 8 is then opened so that the firing fuel, after passing through the mixing tube 7, is injected into the muffler 6. The fuel so introduced is mixed with air at the mixing nozzle 1516, is ignited at the depression 17 and burns in a flame 19.

The pressure built up in the head space of the tank 9 is conducted through the pipe 25 to the head space of the fuel tank 26 which supplies the carburetor 2. If the resonant pulse jet combustion device is operated by the firing fuel, no separate tank 26 for the combustion device fuel is required.

In order to protect the tanks 9 and 26 from undesirable heating, a heat insulating barrier 27 is disposed between these tanks and the mufiler 6. It has been found desirable to keep the fuel feed pipe 41 of the spray nozzle 8 below a temperature at which vapor bubbles form therein, and it is accordingly preferred to provide cooling fins 28 disposed about this pipe in heat exchanging relation therewith. The fuel emerging from the cooled nozzle 8 then passes rapidly through the range of critical coking temperatures.

If a high-boiling fuel, such as diesel oil or gas oil, is used as the firing fuel, the arrangement shown in Fig. 2 is preferably used for fuel introduction. The upwardly bent end 511 of the exhaust pipe 4a and the similarly bent end 16a of the outlet tube 16 project into the muffier 6a. A mixing tube 30 opens into the exhaust pipe and receives gas from the mufiler through an opening 40. A firing fuel supply nozzle 8a projects into the mixing tube 30. The distance between the mouth of the exhaust pipe end a and the connection therewith of the mixing tube 30 is preferably about 10 to centimeters. During the vacuum or suction phase of the pulsating operation of the resonant pulse jet combustion device, the mixing tube 30 is subjected to suction which draws a mixture of firing fuel and exhaust gases into the exhaust pipe 4a. This mixture is intensely heated and finely vaporized in this pipe and is subsequently blown out into the muffler 6a during the next detonation phase of operation. The described apparatus is also effective for adequately preheating high-boiling firing fuels for combustion.

The parts omitted from Figs. 2 and 3 correspond to those shown in Fig. l and described above.

In the modification of Fig. 3, the muffler 6b is in the form of a circular section cone or cyclone separator, and the exhaust pipe 4b opens tangentially into this muffler at its large upper end. The firing fuel falls in drops into the turbulently eddying gases within the muffler from the pipe 8!). As the fuel is carried by the whirling gases to the central outlet tube 16b which leads to the mixing nozzle 15-16, the fuel is substantially completely vaporized. Any solid residues of the fuel collect in a container 33 at the bottom of the mutller 6b from which they may be removed from time to time.

We claim:

1. A combustion heating device comprising the combination with a resonant pulse jet combustion device including a combustion chamber, an elongated exhaust pipe directly connected thereto and forming therewith a resonator and means for automatically feeding fuel and air to said combustion chamber to produce successive detonation phases and intervening vacuum phases of operation, of wall means forming a muffler chamber connected to the mouth of the exhaust pipe, means for introducing a firing fuel into said muffler chamber for vaporization therein, an air mixing nozzle, a firebox, means for conducting the exhaust gas and firing fuel mixture from said mufiler chamber to the air mixing nozzle,

and means for conducting the resulting mixture from the air mixing nozzle to the fire box, the point of entrance of the exhaust pipe into the muffler chamber and the point of exit of the means for conducting the exhaust gases and firing fuel from the muffler chamber being so relatively positioned and the mufiler chamber so constructed that audible frequencies of the gases in said muffler chamber are substantially muffled.

2. A combustion heating device according to claim 1, wherein said means for introducing firing fuel comprises a spray nozzle connected to the muffler chamber and means for injecting the firing fuel into the muffler chamher through the spray nozzle.

3. A combustion heating device according to claim 2, further characterized by the provision of a mixing tube located outside of and connected to the mufller chamber and enclosing the spray nozzle, a fuel feed pipe for said spray nozzle and a fin cooler disposed in heat exchanging relation to said fuel feed pipe.

4. A combustion heating device according to claim 1, wherein said means for introducing firing fuel comprises a mixing tube connected to the exhaust pipe adjacent to but in advance of the mouth of such pipe which opens into the muffler chamber, and in that means are provided for introducing the firing fuel directly into the exhaust pipe through such mixing tube.

5. A combustion heating device according to claim 1, in which the muffler chamber is of circular section, the exhaust pipe of the resonant pulse jet combustion device opens tangentially into the muffler chamber, and wherein said means for introducing the firing fuel supplies said fuel in drops into the zone of the muffier chamber wherein exhaust gases whirl.

6. A combustion heating device according to claim 1 in which the air mixing nozzle is positioned to direct the resulting mixture issuing therefrom into heat-exchange relationship with said combustion chamber.

7. A combustion heating device according to claim 6 in which said combustion chamber has a portion so positioned that on operation of the pulse jet combustion device it is heated to a temperature sufficiently high to ignite the gaseous mixturepassing from the air mixing nozzle to the fire box and said gaseous mixture is caused to be brought into contact with such portion for ignition.

References Cited in the file of this patent UNITED STATES PATENTS 1,861,014 Howard May 31, 1932 2,459,575 Neumann et al. Jan. 18, 1949 2,465,711 Clarkson Mar. 29, 1949 2,643,107 Kamm et al. June 23, 1953 FOREIGN PATENTS 270,783 Switzerland Dec. 16, 1950 

1. A COMBUSTION HEATING DEVICE COMPRISING THE COMBINATION WITH A RESONANT PULSE JET COMBUSTION DEVICE INCLUDING A COMBUSTION CHAMBER, AN ELONGATED EXHAUST DIRECTLY CONNECTED THERETO AND FORMING THEREWITH A RESONATOR AND MEANS FOR AUTOMATICALLY FEEDING FUEL AND AIR TO SAID COMBUSTION CHAMBER TO PRODUCE SUCCESSIVE DETONATION PHASES AND INTERVENING VACUUM PHASES OF OPERATION, OF WALL MEANS FORMING A MUFFLER CHAMBER CONNECTED TO THE MOUTH OF THE EXHAUST PIPE, MEANS FOR INTRODUCING A FIRING FUEL INTO SAID MUFFLER CHAMBER FOR VAPORIZATION THEREIN, AN AIR MIXING NOZZLE, A FIREBOX, MEANS FOR CONDUCTING THE EXHAUST GAS AND FIRING FUEL MIXTURE FROM SAID MUFFLER CHAMBER TO THE AIR MIXING NOZZLE, AND MEANS FOR CONDUCTING THE RESULTING MIXTURE FROM THE AIR MIXING NOZZLE TO THE FIRE BOX, THE POINT OF ENTRANCE OF THE EXHAUST PIPE INTO THE MUFFLER CHAMBER AND THE POINT OF EXIT OF THE MEANS FOR CONDUCTING THE EXHAUST GASES AND FIRING FUEL FROM THE MUFFLER CHAMBER BEING SO RELATIVELY POSITIONED AND THE MUFFLER CHAMBER SO CONSTRUCTED THAT AUDIBLE FREQUENCIES OF THE GASES IN SAID MUFFLER CHAMBER ARE SUBSTANTIALLY MUFFLED. 